CSF, Ventricles & Brain Anatomy
Foramen of Magendie
The foramen of Magendie is the single midline outlet of the fourth ventricle, through which cerebrospinal fluid exits into the spaces around the brain.
In short: Foramen of Magendie
- It is the midline outlet of the fourth ventricle.
- It is a key exit point for CSF.
- Blockage can cause hydrocephalus affecting all ventricles.
- It works alongside the foramina of Luschka.
What it is
The foramen of Magendie is the single, midline opening at the bottom of the fourth ventricle, through which CSF exits into the subarachnoid space (including the cisterna magna behind the brainstem). It is the central outlet of the fourth ventricle.
Understanding Foramen of Magendie
Together with the two side foramina of Luschka, the foramen of Magendie allows CSF to leave the ventricular system and circulate around the brain and spinal cord. If it is blocked — for example, by scarring or a malformation (as can occur in some posterior fossa conditions) — CSF flow out of the ventricles is impaired, which can cause hydrocephalus affecting all four ventricles. It is part of the anatomy considered when identifying where CSF flow is obstructed.
Why it matters
Understanding the foramen of Magendie helps families see how CSF exits the ventricular system through a central outlet, and why blockage here can cause widespread ventricular enlargement.
Common questions
Where is the foramen of Magendie?
In the midline at the bottom of the fourth ventricle.
What does it do?
It lets CSF exit into the spaces around the brain.
Can blockage cause hydrocephalus?
Yes — it can affect all four ventricles.
Bottom line
The foramen of Magendie is the midline outlet of the fourth ventricle for CSF; blockage can cause widespread ventricular enlargement.
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